A new method to synthesize ?-diazoalkylphosphonates with Seyferth-Gilbert reagent under a mild environment

摘要

The reactivity and selectivity of dimethyl (diazomethyl) phosphonate 3 (DAMP) were explored in this research The chemistry of DAMP has been investigated for several decades In previous literature reports the strong base (t-BuOK) was selected to deprotonation DAMP at the low temperature (-78 ℃) and then the aldehyde group could be transferred into the alkyne group by the DAMP anion via the Horner-Wadsworth-Emmons type reaction However there were very few literature reports about the DAMP anion used for nucleophilic substitution reactions and it even needed metal to catalyze the reaction Based on the concept of friendly environment we designed a new synthesis method to prevent the harsh condition The more mild base 1 8-diazabicyclo[5 4 0]undec-7-ene (DBU) was used to promote DAMP under 0 ℃ to room temperature (28 ℃) and the corresponding ?-substituted dimethyl(diazomethyl)phosphonate compounds were synthesized The tolerance of functional group in this reactive condition was also tested The result revealed that products contained the electron-withdrawing group or electron-donating group all had the better yield than before In the last part of our research 4-(bromomethyl)benzaldehyde was taken as the starting material which respectively reacted with DBU and KOH to compare the reaction selectivity between two conditions The isolated products were identified by NMR spectrum and the result demonstrated that DBU-promoted DAMP selectively reacted with benzyl bromide but reserved the aldehyde group However when 4-(bromomethyl) benzaldehyde reacted with the DAMP anion deprotonated by KOH the aldehyde group became the alkyne group and the bromide was replaced by the methoxy group which was from methanol Overall we had developed a new synthetic method that not only has the selectivity but also improves the drawbacks from the previous methods such as mild reaction condition good yield cheaper price and good functional groups tolerance

獎項日期	2017 8月 7
原文	English
監督員	Ho-Hsuan Chou (Supervisor)